CAT and type 2 diabetes mellitus: According to the 2SMR analyses, raised bilirubin levels were linked to a reduced incidence of T2DM (OR = 0.895, 95% CI = 0.813–0.984, Figure 3), and a raised level of catalase showed a slight correlation with a lower risk of T2DM (OR = 0.965, 95% CI = 0.937–0.994, Figure 3).